Organic light emitting diode having an emitter layer with a host and an emitter and having a triplet injection layer comprising the emitter, and methods of use thereof

An organic light emitting diode (OLED) device comprising:

• a transparent electrode;
• an optional hole injection layer;
• a hole transport layer;
• an emitting layer comprising:
• a host and an emitter,
• wherein the host exhibits triplet-triplet annihilation up-conversion,
• wherein the emitter has a band gap and exhibits triplet-triplet annihilation up-conversion,
• wherein the host and the emitter are different, and
• wherein the emitter has a concentration of 5% or more in the emitting layer;
• a triplet injection layer comprising the emitter;
• an electron transport layer;
• an optional electron injection layer;
• and
• a cathode;
• wherein:
• when the optional hole injection layer is present:
• the hole injection layer is in contact with the transparent electrode and the hole transport layer such that the hole injection layer is disposed between the transparent electrode and the hole transport layer;
• and
• the hole transport layer is in contact with the hole injection layer and the emitting layer such that the hole transport layer is disposed between the hole injection layer and the emitting layer;
• and
• when the optional hole injection layer is absent:
• the hole transport layer is in contact with the transparent electrode and the emitting layer such that the hole transport layer is disposed between the transparent electrode and the emitting layer;
• wherein the emitting layer is in contact with the hole transport layer and the triplet injection layer such that the emitting layer is disposed between the hole transport layer and the triplet injection layer;
• wherein the triplet injection layer is in contact with the emitting layer and the electron transport layer such that the triplet injection layer is disposed between the emitting layer and the electron transport layer;
• and
• wherein:
• when the optional electron injection layer is present:
• the electron transport layer is in contact with the triplet injection layer and the electron injection layer such that the electron transport layer is disposed between the triplet injection layer and the electron injection layer;
• and
• the electron injection layer is in contact with the electron transport layer and the cathode such that the electron injection layer is disposed between the electron transport layer and the cathode;
• and
• when the optional electron injection layer is absent:
• the electron transport layer is in contact with the triplet injection layer and the cathode such that the electron transport layer is disposed between the triplet injection layer and the cathode.